An engine generates a rotation force by combusting fuel, and the remaining energy from the combustion of the fuel is exhausted as heat energy. In particular, a coolant absorbs heat energy while circulating through the engine, a heater, and a radiator, and discharges the absorbed heat energy to outside.
When a coolant temperature of the engine is low, viscosity of the oil is increased. Thus, a frictional force is increased, fuel consumption is increased, and a temperature of an exhaust gas is slowly increased so that time for activation of a catalyst is extended, and accordingly, quality of the exhaust gas may be deteriorated. Furthermore, time for normalization of operation of the heater extends so that a passenger or a driver may feel cold.
When the coolant temperature of the engine is excessively high, knocking occurs, and ignition timing needs to be adjusted for suppression of the occurrence of knocking, thereby causing operation deterioration. In addition, when a temperature of lubricant is excessively high, lubrication performance may be deteriorated.
Thus, one integrated flow control valve that controls several cooling elements is applied to maintain a temperature of the coolant at a specific portion of the engine to be high and a temperature of the coolant at other portions to be low.
A block coolant inflow stopping technique for stopping a coolant flowing through a cylinder block has been being applied, and a research for precisely controlling a coolant supplied to the oil cooler has been being conducted.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.